The invention relates to a steering spindle having a section which can be deformed in the event of a crash.
In order to, in the event of a crash, uncouple the movement of the steering gear to the driver caused by the forward vehicle intrusion from the behavior of the steering column with respect to the driver, it is known to equip the steering spindle with a section which deforms in the event of a crash.
For this purpose, a portion of the steering spindle can be formed by a corrugated tube; the steering spindle can have a forward-bent desired bending point; or a bendable shaft or a flexible metal tube can be provided. In addition, for uncoupling the forward vehicle intrusion from the steering column behavior, a swinging arm or a shear element with a shearing surface which is oblique with respect to the steering spindle can be integrated in the steering spindle or the steering spindle can be constructed to be telescopable.
While the corrugated tube and the desired bending point require a high level of force for the deformation and, in the case of bendable shafts and flexible metal tubes, the resistance is unsatisfactory, the telescopable steering spindle has an optimal function only in the case of an axial introduction of force which, however, in the event of a crash, is improbable. In the case of the shear element, it is a disadvantage that, even at a low safety level, for example, in the event of a shocklike loading of a steered wheel, for example, in the off-road operation, a shearing can take place. The disadvantage of the swinging arm is mainly its large space and clearance requirement.
It is an object of the invention to provide a steering spindle with a low requirement with respect to space and clearance and with a high resistance to torsion which, at a low level of force and independently of the force introduction direction, ensures a perfect uncoupling of the forward vehicle intrusion from the steering column behavior in the event of a crash.
According to the invention, this is achieved by means of a steering spindle which can deform in the event of a crash,
wherein a deformable section is formed by a thin-walled container filled with an incompressible flowable material, and a device for opening the container in the event of a crash is provided. Advantageous further developments of the steering spindle according to the invention are indicated in the subclaims.
According to the invention, an axial section of the steering spindle consists of a thin-walled container which is filled with an incompressible flowable material. The container consists, for example, of a metal sheet or a similar deformable thin-wall material.
Like a closed can filled with a liquid, in the closed condition, the container has a high resistance to torsion while, after the opening, while the flowable material emerges, like an opened can, it can easily be twisted and/or compressed.
So that, in the event of a crash, the flowable material can flow out of the container, the steering spindle according to the invention is provided with a device by which the container is opened in the event of a crash.
This device can have different constructions. Thus, an electromagnetic device can be provided for opening the container, such as a solenoid valve or similar shut-off element which, in the event of a crash, is actuated by way of an analysis unit by a crash sensor. In addition, for example, a mechanical device for opening the container can be provided, such as a point, blade or similar penetrating element, which is arranged on the side of a part connected with the steering gear, which side faces the container, which part is displaceably guided with respect to the container, for example, telescopically in a steering spindle section connected with the container. The penetrating element therefore penetrates into one face of the container, whereby immediately at the start of the crash, the forward vehicle intrusion can be uncoupled from the steering column behavior by a deformation of the container. It is also conceivable that the device for opening the container only begins to tear or slits open the latter without penetrating into the interior of the container.
In addition, a pyrotechnic device can be provided for opening the container, which device is ignited by way of an analysis unit by a crash sensor. The analysis unit can define, for example, the safety level and the point in time for initiating the pyrotechnic charge and thus for deforming the container. In the case of a slight crash, the steering capacity can therefore be maintained.
The pyrotechnic device can be formed by a pyrotechnic charge in the interior of the container, which charge, after its ignition by increasing the internal pressure of the container results in the opening of the container. On a face of the container, a pressure chamber with the pyrotechnic charge can also be provided, the flowable material in the container flowing out, for example, on the opposite face of the container.
In order to facilitate the opening of the container and therefore the flowing-out of the flowable material, the faces of the container are preferably provided with a bursting foil or similar desired breaking points.
The pyrotechnic device for opening the container can also be formed by a piston in a cylinder which can be acted upon by the combustion gases of the pyrotechnic charge, the piston being provided with a point or similar penetrating element for opening the container.
The incompressible flowable material in the container can be a liquid, such as water or oil, for example, mineral oil or silicone oil. Firm incompressible, flowable materials can also be used. Combinations of incompressible liquids and solid-state materials are also conceivable.
So that it can flow out of the opening in the container with a low force requirement and at a high speed, the incompressible flowable material must, however, have a slight cohesive resistance. Also, for reasons of weight, light materials are preferred, such as mixtures of liquids and light fillers, particularly hollow microballs, for example, made of glass or plastic.
As a result of the container integrated in the steering spindle according to the invention, in the event of a crash, a secure uncoupling of the forward vehicle intrusion from the steering column behavior is achieved at a low level of force.
Because of its filling with the incompressible flowable material, the container has a rigidity in the driving area which ensures a perfect torque transmission while the elasticity of torsion is minimal.
The container, which is arranged coaxially with respect to the steering spindle, may have a diameter corresponding to the steering spindle, so that no additional space or clearance is required. The function of the steering spindle according to the invention is also independent of the direction of the introduction of force because the opened container will also collapse perfectly at lateral forces.
In order to protect the container and minimize the consequences of a faulty triggering, the steering spindle can have a protective covering, for example, consisting of a woven metallic or synthetic structure, a fiber-reinforced synthetic material or the like, in the area of the container, which protective covering surrounds the container and connects the steering spindle sections with one another which are separated by the container. As a result, the steerability is maintained, although with an increased elasticity, to such an extent that the steering of the vehicle can continue at least to a coasting.
In the following, an embodiment of the steering spindle according to the invention will be explained in detail by means of a drawing.